For aircraft doors as possible closing devices for openings in the aircraft fuselage, which are to be opened by a manual force after a landing even with a pressure difference between cabin (side of the higher pressure) and surrounding environment (side of the lower pressure), there exists the danger, that the operator of the door suffers harm due to the rapid opening movement of the door or also due to the arising airflow from the cabin to the outside. Accidents prove that such endangerments can arise. In order to prevent this, there exists, for example in passenger aircraft, an electrically driven optical warning mechanism consisting of a red lamp in the window area of the door, which begins to blink in connection with an existing differential pressure and a deactivated emergency slide trigger. Thereby, it is to be signaled to the operator, that an operation of the door is potentially dangerous and should not be carried out so long until the pressure equalization has taken place. This is unobjectionable for a normal deplaning of the aircraft. In the case of an emergency evacuation of the aircraft, in which all occupants must have exited from the aircraft within 90 seconds, untrained persons such as passengers would cease or abstain from the operation of the doors due to the blinking warning lamp. The consequence thereof would be a drastically delayed evacuation.
Furthermore, due to the necessary electrical energy supply, the warning function of the blinking lamp is limited to scenarios in which a current supply is available from the onboard power network or grid or an autonomous supply source.